Effects of gene flow and local adaptation on genetic and morphological variation in populations of the tetrafish Astyanax lacustris in the floodplains of southern Pantanal

• Grant number: 18/03969-6
• Support Opportunities: Regular Research Grants
• Start date: July 01, 2018
• End date: June 30, 2020
• Field of knowledge: Biological Sciences - Ecology - Theoretical Ecology
• Principal Investigator: Márcio Silva Araújo
• Grantee: Márcio Silva Araújo
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil
• Associated researchers: Fernando Paiva ; Luiz Eduardo Roland Tavares ; PRIANDA RIOS LABORDA ; Raul Costa Pereira ; Sérgio Furtado dos Reis ; Sergio Ivan Perez

Abstract

The objective of the present proposal is to describe the patterns of genetic and morphological variation in populations of the tetrafish Astyanax lacustris in the floodplains of southern Pantanal in the state of Mato Grosso do Sul and to infer the relative roles of gene flow and local adaptation in the origin of this variation. The tetrafish A. lacustris is a small species (up to 12 cm TL) commonly found in the floodplains of the Pantanal of Mato Grosso do Sul. We will sample populations from three lagoons that connect only occasionally to the Miranda river (low gene flow), three lagoons that connect annually to the river during the flood period (high gene flow) and the population of the Miranda river. Each population will be sampled one time at the end of the dry season (August-September) and at the end of the flood season (February-March). Our general hypotheses are that (i) the populations in lagoons suffer a stronger effect of gene flow than the river population (which is relatively larger) and that (ii) there is an inverse relationship between the degree of gene flow - determined by the frequency and duration of the connection between lagoons and the river during the flood season - and the degree of genetic and morphologic differentitation. Molecular variability will be estimated with the use of microsatelites. Morphological variation will be analyzed with shape variables generated from 17 anatomical landmarks and 6 semi-landmarks commonly used to quantify body shape in fishes. The presence of diversifying natural selection will be tested with models of quantitative genetics. (AU)